JPS61176954A - Fixing method of heating roller - Google Patents

Abstract

PURPOSE:To reduce offsets and the scatter of pictures and to make the separation of toner from a roller excellent so as to make high-speed continuous fixing, by respectively providing elastic layers and thin mold-releasable resin surface layers having thicknesses thinner than those of the elastic layers on the surfaces of a fixing roller and press roller. CONSTITUTION:Elastic layers 12 and 22 and thin mold-releasable resin surface layers 13 and 23 having thicknesses which are thinner than those of the elastic layers are respectively formed on the surfaces of a fixing roller 1 and press roller 2. The thickness t3 of the elastic layer 22 of the roller 22 is made thicker than the thickness t1 of the elastic layer 12 of the roller 1 and the thickness t4 of the surface layer 23 of the roller 2 is made thinner than that t2 of the roller 1. Therefore, offsets and scatter of pictures to the fixing roller 1 are reduced and high-speed continuous fixing, in which separation between toner and roller 1 is excellent, can be performed with a fixing means which is durable for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating roller fixing method used in electrophotography, electrostatic printing, and the like.

The present invention particularly relates to a fixing method that is effective for multifunctional recording apparatuses that perform multiple recordings on one recording material at high speed, such as double-sided recording (copying) and multiplex recording.

<Conventional technology and its problems> Although conventional image recording devices have many functions, they mainly perform low-speed recording, and conversely, they do not have many high-speed recording functions to begin with. Therefore, the requirements for fixing methods and devices are The conditions are not so strict, my friend.

Multi-functional high-speed recording equipment has fixing and offset properties.

Imaging properties, curling properties after fixing, roller durability, etc. are required. In order to improve the releasability from the fixing roller, low-molecular-weight polyolefin is added to the toner, the softening point of the resin is lowered to create a toner that easily melts when heated, or the side that comes into contact with the undetermined layer image has been developed. Studies have been conducted to satisfy the above conditions by providing a relatively thin elastic layer 71) on a roller (hereinafter referred to as a fixing roller) and a pressure roller.

However, the agglomeration resistance of the toner deteriorates, and the recording material wraps around the fixing roller because the fixing roller and recording material are not separated quickly, resulting in jams and fixed images caused by the separation claw. New problems have arisen as the product becomes more susceptible to damage.

Objectives> The objectives of the present invention are to enable high-speed continuous fixing processing, reduce offset to the fixing roller, minimize curling of the recording material, and reduce image scattering; 11! A heated roller fixing method that uses a fixing means with excellent slag properties and excellent durability that does not wear off over a long period of time, and uses toner that has low agglomeration and is extremely easy to separate from the fixing roller and fix. It provides:

Explanation> Hereinafter, the roller that comes into contact with the unfixed hoe will be referred to as the fixing roller, and the roller that will come into contact with the back side of the recording material or one side that has been fixed (during double-sided recording) will be referred to as the pressure roller. .

Here, to briefly summarize the present invention in comparison with Examples, the present invention has two pairs of fixing rows for fixing an unfixed object to a recording material, which are relatively thin (t) on the side in contact with the unfixed object. ,)
A fixing roller l having a thin (t) releasable resin surface layer 13 on the elastic layer 12 and having a heating means 3 inside, and a fixing roller l having a thickness υ thicker than the elastic layer 12 of the fixing roller l. (t,
) A pressure roller 2 having a thin (t4) releasable resin thin surface layer 23 on the elastic layer 22, the thickness of which is less than the elastic layer 22, and the relationship f, where the thicknesses thereof are ta < tt < tt < ta. An inorganic fine powder t'' containing a colorant and a binder resin and having a particle size of 0.1 to 5μ is produced using a Mankufu fixing device f/l.
The present invention relates to a heating roller fixing method characterized in that a toner having a content of 1 to 5% by weight is used.

According to the method of the present invention, the above-mentioned structure can withstand long-term use, and furthermore, it is possible to minimize curling of the recording material, produce less offset, have excellent fixing properties, and obtain good image quality. can. In addition, the roller pair can be prevented from becoming dirty, the recording material can be less likely to be wound around, and the occurrence of jams can be greatly reduced.

FIG. 1 shows an overview of a fixing device implemented as a fixing means for carrying out the method of the present invention, and FIG. 2 shows an explanatory diagram of the main part configuration of the fixing device implemented in FIG. 1.

In FIG. 1, l is a relatively thin elastic layer 12i made of silicone rubber, fluororubber, etc., provided on a core metal 11 with good thermal conductivity such as aluminum, and a tetrafluoroethylene resin hardened layer 12i is provided on the upper layer. Copolymer of 70-roalkoxyethylene resin (hereinafter referred to as PF)
A), a 7-layer resin such as polytetrafluoroethylene resin (PTFE) is made thinner than the elastic layer 12 (in this example, the thickness is 1 μ to 70 μm).
The fixing roller is coated with a resin layer (predetermined thickness within the μ range).

2 is a pressure roller that rotates in pressure contact with the fixing roller l;
On a core metal 21 made of stainless steel, iron, etc., a relatively thick elastic layer 22 made of silicone rubber, fluororubber, etc. is provided, which is thicker than the elastic layer 12, and the upper layer is made of PFA, PTFE, hexafluoroethylene propylene ( This is a pressurized a-ra coated with a mixed layer of fluororesin and fluororubber such as PEP (hereinafter referred to as PEP) thinner than the thick elastic layer 22 (in this example, a predetermined thickness within the range of 10μ to 100μ).

Due to this mixed layer, on the surface of the pressure roller, a resin surface layer consisting mostly of fluororesin, which is formed by lifting the fluororesin during firing, exists with a thickness of several micrometers.

3 is a heater such as a halogen lamp for heating the fixing roller from inside, and the fixing roller surface temperature is determined by the heater 3, the temperature detection element 4, and the control means 31.
The temperature is always maintained at the optimum temperature for toner melting.

Reference numeral 5 denotes an anti-offset liquid applying means which also serves as a cleaning means for applying an anti-offset liquid such as silicone oil to the surface of the fixing roller. The application means 5 may be felt-like, but in this example a web is used.

The web 51 containing the anti-offset liquid is brought into contact with an elastic pressure roller 52 such as silicone sponge and a fixing roller 1, and a small amount of the anti-offset liquid is applied to the surface of the fixing roller 1. Further, the web 51 is
3, the web is gradually wound up from the supply roller 54, and the contact surface of the web to the fixing roller I can be sequentially determined by a control means (not shown).

The recording paper P carrying the unfixed toner image T is transported to the entrance guide 6.
The toner image T is fixed on the recording paper P by passing between the roller pair 1.2 while being guided by the toner image T. A separation claw 4I that comes into contact with the surface of the roller 1 is provided to separate the recording material from the roller surface l.

In the above configuration, an important configuration is the thickness t of the elastic layer 12 of the fixing roller 1, as shown in FIG.

Thickness tl of resin layer I3 of fixing roller l, thickness t of elastic layer 22 of pressure roller 2, I resin layer 23 of pressure roller 2
The thickness t4 has the following relationship.

That is, at roller l tl > tt s at roller 2
tx > t4* 1 between rollers 1 and 2. (1, (1, (1,

Before explaining specific numerical examples, a double-sided recording apparatus will be explained as an apparatus in which the present invention is particularly effective and the effects obtained by applying the invention are more stable.

The apparatus shown in FIG. 3 has a double forming section for forming an image on paper by electrophotographic copying. This image forming process is well known and its explanation will be omitted.

Further, in this example, normal recording paper is used as the transfer material.

In FIG. 3, a copying machine 17. The double-sided device section 18 is composed of an automatic document circulation feeder (RDF) 19 and a paper binding device (stapler) 20. The image forming process in the copying machine 17 is known as described above. The original on the original table glass 9 is scanned by the optical system 10, and the reflected light is cast onto the photoreceptor 24 to form an electrostatic latent image, and the developing device 25 produces a visible edge as a toner artist. become

The paper onto which this toner image is transferred is fed from a paper feed table 27 by a paper feed roller 28, and is aligned with the toner image on the photoreceptor 24 by a registration roller 29. Thereafter, the toner artist is transferred onto the surface of the paper by the transfer charger 30.

Next, the toner is separated from the surface of the photoreceptor by the separation charger 14 and conveyed to the fixing device 15 by the belt 35 . Incidentally, in the peripheral area of the photoreceptor, various known means such as a rete, which are necessary for image formation other than those described above, are arranged. In the case of one-sided copying, the paper on which the toner image has been fixed after passing through the fixing device 36 is guided by this guide 38 and discharged to the sorter 20, since the switching guide 38 is located at the dotted line position in the figure. be done. However, in the case of double-sided copying, when the single-sided copying is completed, the switching guide 38 is at the solid line position in the figure, so the paper is guided to the duplexing device section 18 below by this guide 38. .

The screen device section 18 receives the paper whose first side has been copied by the copying machine 17, and feeds the paper again when the next second side is to be copied.

In this embodiment, a preliminary paper feed table P is provided, and when this paper feed table P is selected in the main body of the copying machine 17, the paper feed roller 42 moves the paper in the preliminary paper feed table P. It is also possible to feed the paper and transport it to the transfer section of the main body. The paper guided to the duplexer section 18 by the switching guide 38 and roller pair 40 described above is transferred to the roller pair 4.
45 and 46 onto a tray 47 tilted toward the upper right side of the figure. At this time, the lateral positions of the sheets are aligned by the guide side walls 48 that determine the lateral positions of the sheets (in the direction perpendicular to the transport direction). Next, the rear end of the sheet of paper is pressed downward by a rotating body 49 having elastic protrusions on the outer periphery, and the paper is pushed diagonally downward (
left side of the figure). At this time, a stop member 50, the details of which will be described later, and rollers 151 and 152 that cooperate with the stop member 150 feed out the sheets of paper successively stored in the tray 47 in a shifted state.

The fed paper is transferred between the roller 153 and this row 2153.
rollers 154, 55, 56
．． A belt 58 stretched over the belt 57 makes a U-turn, and the paper is conveyed with the front and back sides reversed. A guide 59 is disposed above the belt 58 to sandwich the belt 58 and guide the row 256.
A presser roller 60 is disposed opposite to the sheet, and these rollers ensure that the sheet is conveyed on the belt 58 reliably. Furthermore, these guides 59 and rollers 60 can be opened and closed integrally), making it easier to remove jammed sheets from the belt 58 when a jam occurs. A roller 61 for refeeding paper is located opposite the roller 57 on which the belt 58 is stretched.
is disposed, and works in cooperation with a sensor 62 for detecting paper passage and a pair of conveyance rollers 63 to feed the sheets conveyed by the belt 58 one by one from the beginning toward the right in the figure.
Thereafter, it is conveyed to registration rollers 29 through roller pairs 64 and 43 in sequence. The paper is periodically sent to the transfer section by the registration rollers 29 according to the image on the second side formed on the surface of the photoreceptor, and the image is transferred onto the second side. After the transfer is completed, the paper is separated from the surface of the photoreceptor, the image is fixed by the fixing device 15, and the paper is conveyed to the switching guide 38.

At this point, the guide 38 is at the dotted line position in the figure, so
It is ejected from the aircraft. The duplex device unit 18 is a tortoise that enables double-sided copying by repeating such operations. Furthermore, as can be seen from the figure, the paper after fixing tends to warp toward the image forming surface due to the structure of the fixing roller of the fixing device 15 and the paper conveyance path immediately after fixing. However, in this example, in order to change the conveyance direction of the paper, the paper is curved (by roller l) toward the image forming surface side, and moreover, it takes more time to pass through the curved portion, so that the paper is It is possible to reduce anti-shi (curl) by 1.

The automatic document circulation feeder (RDF) 19 is connected to the document loading table 6.
The next original O stacked on the top 5 is separated and pulled out one by one from the bottom of the belt 66 and 67. Thereafter, the original 0 is turned in a U-turn so that the original surface is facing downward, and then conveyed over the original glass 9 to a predetermined position Il by a bell 16 suspended over its entire length. . In this way, the image surface of the transported document O is scanned by the optical system 10 and is copied onto a sheet of paper as described above. The scanned document is transferred to the roller 69 by the reversal of the bell) 16.
After being conveyed through the spaces between the originals and 70, the originals are loaded onto the stacking table 65 by the pair of rollers 75 and discharged onto the top of the next original. By repeating this operation, the originals stacked on the stacking table 65 can be copied in order. Note that even in the case of double-sided originals, the belt is o-rough 2.7
Due to the functions of 3°74.76.77.78 and 79,
By flipping the front and back of the document and scanning both sides of the document,
Copies can be made. Since such reversing operation is not directly related to the present invention, its explanation will be omitted.

The automatic stitching device IT (stapler) 20 stitches the copied sheets discharged from the copying machine 17. This stapler 520 has a tray 81 for stacking paper. A connection path 82 to another paper processing device, for example a sorter, is provided. When binding is specified, the paper conveyance path is switched to the path toward the opening and closing pair 83, and the sheets are stacked on the tray 84.

When a predetermined number of sheets are stacked on this tray 84, the stapling device 85 is activated and a binding operation is performed. The bound paper bundle is placed on a loading table 86. After this, the next sheet to be bound can be received.

In the toner according to the present invention, any binder resin can be selected. For example, polystyrene.

Monopolymers of styrene and its substituted products such as poly-p-chlorostyrene and polyvinyltoluene, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene Copolymer.

Styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-methacrylate Ethyl acid copolymer, styrene-butyl methacrylate copolymer.

・Styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene- Butadiene copolymer, styrene-imprene copolymer.

Styrene-acrylonitrile-indene copolymer.

Styrenic copolymers such as styrene-maleic acid copolymers and styrene-maleic acid ester copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, and polyvinyl acetate.

polyethylene, polypropylene, polyester.

Polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyamide, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin.

Aromatic petroleum resins, chlorinated paraffins, paraffin waxes, etc. can be used alone or in combination.

If necessary, additives may be mixed into the toner of the present invention within a range that does not impair the properties of the toner. Examples of such additives include lubricants such as Teflon, zinc stearate, and polyvinylidene fluoride.

or fixing aids (e.g. low molecular weight polyethylene).

(low molecular weight polypropylene, etc.), tin oxide, etc. may be used as an electric sensitivity imparting agent. Charge control.

Carbon black for purposes such as preventing agglomeration.

Nigrosine, metal complex salts, silica powder, etc. may be added.

In order to use the toner of the present invention as a magnetic toner, it may contain magnetic powder. As such magnetic powder,
A substance that is magnetized by being placed in a magnetic field is used, and includes powders of ferromagnetic metals such as iron, cobalt, and nickel, or alloys and compounds of magnetite)+r-iron oxide efrite. The content of this magnetic powder is 15% based on the weight of the toner.
-70 weight ratio is preferable.

For toner, use iron powder or glass peas as needed.

It is mixed with carrier particles such as nickel powder or ferrite powder and used as a toner for electrical latent images.

In the toner of the present invention, the inorganic fine powder having a particle size of 0.1 to 5# is used as a release aid, and any powder can be selected. For example, iron oxide, chromium oxide, titanium oxide, magnesium titanate, calcium titanate, strontium titanate, lanthanum titanate, zinc titanate, bismuth titanate.

Cerium oxide, zirconium oxide, aluminum oxide,
Examples include zinc oxide and calcium carbonate.

Among these, strontium titanate and cerium oxide are preferred. The above-mentioned fine powders may be used alone or in a blend of two or more, and the amount added is preferably 1 to 5% by weight based on the weight of the toner.

The following will be described in detail according to examples.

Example-1 The fixing roller l is made of fluororubber coated with PFA, with an outer diameter of 59.3 mm at the center and 59.3 mm at both ends.
+200 μm (a roller with a reverse crown amount of 10100 A was used).

The rollers were manufactured as shown below.

As a core metal, the diameter of the center part is 5 m3 mm and 1. An aluminum core metal with a reverse crown amount of 100 μm was prepared, and its surface was sandblasted, degreased and dried, and then a fluororubber sheet was wrapped around it via a primer, press-cured at 150°C for 40 minutes, and then vulcanized at 200°C. After secondary vulcanization at ℃ for 2 hours, it was uniformly ground to a rubber inner thickness of 0.48 vmctt').

Then, PFA was added to 20 μm (ts') via the primer.
) Thick electrostatic coating was applied and baked at 310°C for 30 minutes.

As the pressure roller 2, a roller having an outer diameter of 60.0 m and having a mixed layer of fluororubber and fluororesin coated on silicone rubber was used.

This roller was manufactured as shown below.

As a core metal, prepare an iron core metal with an outer diameter of 5 m (1 m), sandblast its surface, degrease it and dry it, wrap it with a silicone rubber sheet through a primer,
Press vulcanization was performed at 0°C for 30 minutes, followed by secondary vulcanization at 200°C for 1 hour, and the rubber was ground to a thickness of 4.98 m (tl'). Furthermore, a mixture of fluororubber and fluororesin was applied to this rubber roller to a thickness of 50 μm, and an infrared heater was used to heat the roller.
After drying for 15 minutes, dry at 150℃ for 30 minutes, then at 280℃
The mixture was baked for 40 minutes to produce a pressure roller with a wide diameter of 60 m.

During the above firing, the roller surface tends to become a low surface energy surface, so the fluororesin component comes to the surface due to micro-Brownian motion.

When the surface layer is covered with the fluororesin and becomes a sufficiently low surface energy surface, the movement of the fluororesin to the surface layer stops.

As a result, the surface layer of the pressure roller has a thickness of 2 to 3 A due to the fluororesin content, and the layer below it is a layer containing more fluororubber. By the way, as a fluororesin, FE
P, PFA, PTFE, etc. can be used, and the ratio of fluororubber to fluororesin is preferably 20:1 to 1:2. The above rubber hardness for both rollers is 20 to 80 degrees (J
/SA).

Both rollers are brought into contact with each other at a total pressure of 60, and at a circumferential speed of 340.
m/sec (50 sheets/min of A4 paper) to form the fixing device 15 in FIG.

On the other hand, styrene, n-butyl acrylate, 2-ethylhexyl acrylate terpolymer io.

parts, low molecular weight polypropylene 2 parts, carbon black 8 parts
The mixture consisting of 50% and 100% was heated and kneaded using a roll mill. After cooling this, it was crushed into a coarse powder using a cutter mill, and further finely pulverized using a supersonic jet mill to obtain a fine powder with an average particle size of about 8μ, and 3% by weight of cerium oxide was added thereto, and thoroughly stirred and mixed using a coffee barrel. The resulting product was used as toner. Fifteen parts of this toner was mixed with 85 parts of carrier iron powder and supplied to the apparatus shown in FIG. 3, where 100,000 sheets of automatic screen printing were carried out.

As a result, there is almost no offset to the fixing roller, the recording material is separated very smoothly, there is little curling, and the fixing device, including the fixing roller and pressure roller, is free from scratches and peeling. It didn't happen at all. The resulting image had good fixing properties, few scattering marks, and high sharpness.

Example-2 Polyoxypropylene (2,2)-2,2-bis(4-
A mixture consisting of 100 parts of a polyester resin synthesized from (hydroxyphenyl)propane, terephthalic acid, alkyl-substituted cono-phosphoric acid, and trimellitic acid, 2 parts of low molecular weight polypropylene, 60 parts of a magnetic material, and 2 parts of a metal complex salt was heated and kneaded in a roll mill. did. After allowing this to cool, it was crushed using a cutter mill and finely pulverized using a supersonic jet hull to obtain a fine powder with an average particle size of 12 μm. Further, 3% by weight of strontium titanate and 0.5% by weight of silica powder were added, thoroughly stirred and mixed using a coffee grinder, and then supplied to the apparatus shown in Figure 3. Automatic double-sided printing of 100,000 sheets was carried out in the same manner as in Example 1. did.

As a result, there is almost no offset to the fixing roller,
The recording material was separated very smoothly, with little curling, and the fixing device, including the fixing roller and pressure roller, did not have any scratches or peeling. The obtained image steel had good fixing properties, few scattering, and high image quality with high sharpness.

Comparative Example 1 The same toner as in Example 1 except that cerium oxide was not added to the toner was supplied to the apparatus shown in FIG. 3, and 100,000 sheets were subjected to automatic duplex printing.

As a result, the offset was significant and the recording material was wrapped around the fixing roller, and after 10,000 sheets were automatically developed on both sides, jams occurred frequently, making it impossible to continue the experiment. Even before 10,000 sheets, the recording material curled significantly and jams occurred. The nine images obtained had a lot of scattering and were of poor quality with poor sharpness.

Comparative Example 2 The same toner as in Example 2 except that strontium titanate was not added was supplied to the apparatus shown in FIG. 3, and automatic double-sided development was carried out on 10,000 sheets.

As a result, the offset was significant and the recording material was wrapped around the fixing roller, and after 10,000 sheets were automatically developed on both sides, jams occurred frequently, making it impossible to continue the experiment.

Even before 10,000 sheets were printed, the recording material curled significantly and jams occurred. The resulting image had a lot of scattering (scattering) and poor sharpness.

Comparative Example-3 As the fixing row 21, 30 μm thick PT was placed on the aluminum core bar.
A roller coated with FE or PFA; A roller whose entire iron core was coated with 51 parts of heat-curable silicone rubber was used as the pressure roller.

Both rollers are brought into contact with each other at a total pressure of 60Kf and at a circumferential speed of 340m.
The fixing device 15 in FIG. 3 was set to l sec (50 A4 sheets/min).

The toner of Example-1 was supplied to the apparatus shown in FIG.
10,000-sheet automatic double-sided printing was carried out.

As a result, the fixing performance was incomplete, and when the image on the first side was conveyed at the same time during double-sided copying, it was rubbed against the surface of the pressure roller, resulting in image defects.

Furthermore, the offset was significant and the recording material was wrapped around the fixing roller, and after 10,000 sheets were automatically duplexed, jams occurred frequently, making it impossible to continue the experiment. Even before 10,000 sheets, the recording material curled significantly and jams occurred. The obtained image had many splatters and poor sharpness.

[Brief explanation of drawings]

FIG. 1 shows a schematic explanatory diagram of a specific fixing device for carrying out the method of the present invention, FIG. 2 shows an explanatory diagram of the main part configuration of the fixing device shown in FIG. 1, and FIG. 1 is a schematic explanatory diagram of a copying machine provided with the fixing device shown in FIG. ]... Fixing roller, 2... Pressure roller, 3... Heater, 15... Fixing device, 17... Copying machine, 18...
・Double-sided device section.

Claims (2)

[Claims] (1) Contains a colorant and a binder resin, and has a particle size of 0.
A recording material holding a toner image made of an electrostatic charge developing toner containing 1 to 5% by weight of inorganic fine powder of 1 to 5 μm is placed on a relatively thin elastic layer on the side in contact with the unfixed object. A fixing roller having a thin surface layer of releasable resin and having a heating means inside, and a thin surface layer of releasable resin having a thickness equal to or less than the elastic layer on the elastic layer thicker than the elastic layer of the fixing roller. By a fixing means having a fixing roller pair consisting of a pressure roller, the thickness of the release resin thin surface layer of the fixing roller is smaller than the thickness of the release resin thin surface layer of the pressure roller, A heating roller fixing method characterized by fixing the toner image on a recording material. (2) In the fixing roller, the elastic layer is made of fluororubber or silicone rubber, the resin thin surface layer is made of fluororesin, and the pressure roller is made of a rubber material on the elastic layer of fluororubber or silicone rubber. 2. The heating roller fixing method according to claim 1, further comprising a resin thin surface layer formed from a mixture of a resin material and a resin material.